change pgsql to postgres

src/test/regress/expected/rules.out

@@ -951,7 +951,7 @@ QUERY: UPDATE shoelace_data SET sl_avail = 6 WHERE  sl_name = 'sl7';
 QUERY: SELECT * FROM shoelace_log;
 sl_name   |sl_avail|log_who|log_when
 ----------+--------+-------+--------
-sl7       |       6|pgsql  |epoch   
+sl7       |       6|postgres|epoch   
 (1 row)
 
 QUERY:     CREATE RULE shoelace_ins AS ON INSERT TO shoelace
@@ -1021,10 +1021,10 @@ sl6       |      20|brown     |   0.9|m       |       90
 QUERY: SELECT * FROM shoelace_log;
 sl_name   |sl_avail|log_who|log_when
 ----------+--------+-------+--------
-sl7       |       6|pgsql  |epoch   
-sl3       |      10|pgsql  |epoch   
-sl6       |      20|pgsql  |epoch   
-sl8       |      21|pgsql  |epoch   
+sl7       |       6|postgres|epoch   
+sl3       |      10|postgres|epoch   
+sl6       |      20|postgres|epoch   
+sl8       |      21|postgres|epoch   
 (4 rows)
 
 QUERY:     CREATE VIEW shoelace_obsolete AS